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Volume 40 (1999 - 200･･･
- Issue 6 Pages 333-
- Issue 5 Pages 260-
- Issue 4 Pages 196-
- Issue 3 Pages 124-
- Issue 2 Pages 60-
- Issue 1 Pages 2-
Volume 40, Issue 4
Displaying 1-5 of 5 articles from this issue
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Hideki INAGAKI1999 Volume 40 Issue 4 Pages 196-206
Published: October 10, 1999
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSThis paper describes an occurreNce of trees fallen by storm caused by typhoon 9807 on September 22th, 1998 and the following slope failures in Hichisoucho, Gifu prefecture.
The author investigates geology, vegetation and ground condition from simple penetration test to clarify the characteristics of forest damages and damages of grounds.
The results of this study are summarized as follows;
1) Trees fallen by storm are much in afforested coniferous forest. However they are little in broadleaved forest.
2) Most amount of disaster by fallen trees occurs the slope on the ground conditions where basement rock is shallow in depth, moreover, where do not thin out a forest.
3) Damage of grounds for trees fallen by storm is regarded as Nc≤2 by simple penetration test. The damage is much on the slope afforested by coniferous trees such as white cedar and Japanese cedar. In broadleaved forest, the damage is little.
4) Slope failures on damaged grounds for trees fallen by storm occur along the gentle valley caused on concentration of surface water and ground water.
5) Slope failures on the ground damaged for trees fallen by storm are characterized as many following occurrence of debris flows, because of including many fallen trees.View full abstractDownload PDF (2226K) -
A Case Study in Kuji Underground Rock Cavern SiteOkgon CHOI, Hiroyuki TOSAKA, Keji KOJIMA1999 Volume 40 Issue 4 Pages 207-219
Published: October 10, 1999
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSFrom the point of fracture morphology, certain characteristic form is produced with growing fracture segments and their jogs, such as en echelon, shear lenses and flower structure, so that segmented structure makes a fault line discontinuous at around jogs, place to place. Based upon such morphological aspect, we can understand better the natural structure of fracture system, and hence, we might estimate better the actual hydraulic field that affects much on the flow of groundwater and mass transport.
In this paper, the authors try to reconstruct the segmented structure of fracture zones around the large rock caverns, utilizing detailed description of fault occurrences obtained on the cavern walls. The fracture occurrences are classified into 7 patterns, and adding fracture geometrical information such as strike and dip, the segmented bodies and jogs are identified. The segmented fault structure map is presented, and its appropriateness is checked and discussed.View full abstractDownload PDF (3854K) -
Yuji KANAORI, Kenji KOBAYASHI, Yasunobu ANNO, Takashi WARIGAYA, Tetsur ...1999 Volume 40 Issue 4 Pages 220-230
Published: October 10, 1999
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSThis paper describes the geology of the fault outcrop which was found at the river bed of the Abu River, in the proximity of the epicenter of the M6.1 Northern Yamaguchi Prefecture earthquake of June 25, 1997. Data of house damage caused by the earthquake are reexamined, in order to evaluate the relationship between the seismogenic fault, the fault outcrop, and damaged zones. The fault outcrop is located in the northeastern part of the Sakota-Ikumo fault. Although this fault was inferred as a geological boundary, the existence of the fault has not been confirmed. In the fault outcrop, a NE-SW-trending, more than 5-meter wide cataclastic zone is extensively developed. Within the cataclastic zone, fault gouge zones with a maximum width of 50 cm are arranged left-steppingly in en echelon, indicating the right-lateral sense of the movement. This sense is consistent with that of the focal mechanism of the Northern Yamaguchi Prefecture earthquake. Its aftershocks also occurred sporadically along the northeastern part of the Sakota-Ikumo fault. On the other hand, the ratio of house damaging is defined as the ratio of the total number of damaged houses to the number of families in a community. The house damaging ratio is calculated for each community of Ato Town and Mutsumi Village, Abu County, Yamaguchi prefecture. The highest ratio is obtained in the Ikumo-Nishibun community, which is located on the Sakota-Ikumo fault, and 5 km southwest of the epicenter of the Northern Yamaguchi Prefecture earthquake. Almost all house-damaged communities are included in a circle with the radius of 10 kilometers and the circle is centered at the Ikumo-Nishibun community. The movement sense from the fault gouge arrangement and distribution of the damaged houses supports the probability that the Northern Yamaguchi Prefecture earthquake was generated by the motion of the northeastern part of the Sakota-Ikumo fault.View full abstractDownload PDF (4400K) -
Hideo KIYA1999 Volume 40 Issue 4 Pages 231-239
Published: October 10, 1999
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSFace collapse due to water seeping into sandy ground constitutes a big factor to decrease the safety of tunnel construction. This paper reports a case study of accumulated tunnel construction data to develop a new method of estimating the tunnel face stability. In the case study, I investigated the conditions that determine the occurrence of wash-out, factors interrelated with water inflow and physical properties of the face, in a multivariate analysis. The results of the analysis are as follows.
1. The critical amount of water inflow (Q) at the tunnel face, to cause a wash-out face is 200 to 300l/min. When Q is over 500l/min, wash-out invariably occurs no matter how favorable other indices are.
2. Physical properties closely related with the face stability include the fine grain content, uniformity coefficient, specific granular gravity of soil and 60% grain diameter.
Although these factors are closely related to the face stability, they don't provide the degree of face stability. This is because the face wash-out must be considered to occur when the power of ground water penetrating into the tunnel inner section exceeds the power of the tunnel face holding its integrity, or the ability that depends essentially on the conditions of ground. This means that the integrity of face should be evaluated in terms of the balance between these two types of power.View full abstractDownload PDF (1792K) -
Ming ZHANG, Manabu TAKAHASHI, Tetsuro ESAKI1999 Volume 40 Issue 4 Pages 240-246
Published: October 10, 1999
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSDownload PDF (1579K)
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